This statement is telling the compiler that you have a static method called Start_Data_Command_04 in the class The_User_Clicked_A_Button_Called. Plainly, from the definition of this method, this is not right - this method is actually an instance method. So, you either have to declare an instance of The_User_Clicked_A_Button_Called using new The_User_Clicked_A_Button_Called().userClicked.Start_Data_Command_04(); or you have to add the static modifier to Start_Data_Command_04.

...then the second error ("Error 1" in my initial example) goes away, but the first one ("Error 2") remains.

My attempts to declare an instance of the method produced more compiler errros.

If you (or anyone who's reading) could tell me the syntax of how to declare an instance of the method in question, I thank you.

More importantly, and an even greater value, would be to show me how to find the syntax for myself.

Performing five or ten different searches on Google and Bing, (and MSDN, which is really Bing, as I understand it) using my best guess of how to phrase it, (e.g., with search phrases like, "C#, The specific syntax for Declaring an instance of a static method in another class" and so on) I did not immediately see an example of the syntax for declaring an instance of a static method in another class.

Lobster Thermidor aux crevettes with a Mornay sauce, served in a Provençale manner with shallots and aubergines, garnished with truffle pate, brandy and a fried egg on top and Spam - Monty Python Spam Sketch

This is actually meant as a comment.
It appears that you are using a very non-standard naming convention in your code. This actually makes the code much more difficult for a another developer to read as we all become accustomed to specific casing and naming methodologies. It's all good if this is just something you are writing for yourself, but habits are hard to break and if you work on commercial code with naming schemes like this, you may run into some developers who won't take kindly to it.
You should take a look at Camel Casing[^]. This is the most common way that CSharp developers write code, and if used correctly will be much appreciated by other developers who will have to look at your code sometime. I have taken the liberty of taking one of your methods above to show you what I mean. Cheers.